Generally, in order for the isolation of a high frequency circuit to be sufficiently high within the operating frequencies of the circuit, the sizes of a high frequency module and its packaging are designed such that the cutoff frequency is sufficiently high when a waveguide is configured, and the resonant frequency is sufficiently high when a cavity is configured.
For example, in a high frequency module described in Patent Literature 1, a space in the high frequency module in which a semiconductor chip is mounted, namely, a cavity, is formed to be a winners podium shape or a three-step winners podium shape, and consequently, the cavity resonant frequency or the waveguide cutoff frequency is increased.
Further, since a high frequency package generates a large amount of heat in general, it is required to provide a structure for heat dissipation.
For example, in the high frequency module described in Patent Literature 2, heat radiating fins are integrally formed with a metal casing in which a high frequency package is mounted, and a thermally conductive sheet is arranged between the high frequency package and the metal casing to enhance the heat dissipation performance of the high frequency package.